The objective of this multi-center, prospective, placebo-controlled, randomized study is to compare oral conditionally essential amino acid (CEAA) supplementation for decreasing the key postoperative complications of fracture-related infection, fracture nonunion, and skeletal muscle wasting with a placebo control (PC) after lower extremity fracture fixation. Investigators hypothesize that perioperative oral supplementation with an investigational CEAA supplement (ICS) will reduce postoperative fracture-related infections, fracture nonunion rates, and skeletal muscle wasting in patients with traumatic lower extremity fractures. This is supported by strong pilot data. Conducting a randomized controlled trial at five civilian tertiary referral centers and one military treatment facility will further study the potential benefits of oral CEAA supplementation for preventing the stated key postoperative complications in patients following high energy lower extremity orthopedic trauma. This low cost, low risk intervention has demonstrated potential to expedite Warfighter return to duty as well as potentially reducing delayed limb amputations and mortality in severely injured patients.

Inclusion Criteria:

1. Adults age 18-55 years
2. Open or closed fracture of the lower extremity including femur, tibia and/or fibula, calcaneus, talus, Lisfranc joint (OTA/AO 31, 32, 33, 41, 42, 43, 44, 4F, 81, 82, 83, 85)
3. Ability to begin supplementation within 72 hours of injury

Exclusion Criteria:

1. BMI <18.5 kg/m 2 (underweight) or BMI > 45 kg/m 2 (severe obesity) to exclude patients with severely increased baseline risk of adverse outcome due to preoperative poor nutrition
2. Non-ambulatory prior to injury
3. Currently pregnant
4. Medical contraindication to CEAA supplementation (e.g., phenylketonuria)
5. Inability to provide informed consent due to intellectual disability
6. Protected populations (e.g., prisoners)
7. Inability to follow up (e.g., homeless at time of surgery, home address out of state of treating facility)
8. Documented dementia, mild or moderate traumatic brain injury
9. Inability to consume supplement or placebo due to head or neck trauma
10. Low-energy fragility fracture (i.e. ground level falls)
11. Pathologic fracture (i.e. fracture through site of compromised bone due to infection, neoplasm, documented osteoporosis, metabolic bone disease from conditions such as end stage renal disease, osteomalacia, hypophosphatemic rickets, renal osteodystrophy, osteofibrous dysplasia)